Field
The present invention relates to a semiconductor device, and more particularly, to a light-emitting diode (LED).
Discussion of the Background
An LED is a device having an n-type semiconductor layer, a p-type semiconductor layer, and an active layer disposed between the n-type and p-type semiconductor layers. When a forward electric field is applied to the n-type and p-type semiconductor layers, electrons and holes are injected into the active layer, and the injected electrons and holes are recombined in the active layer to emit light.
The efficiency of such an LED is determined according to internal quantum efficiency and external quantum efficiency, which is light extraction efficiency. As a method for improving light extraction efficiency, there is a method of forming concave-convex patterns on a substrate like a patterned sapphire substrate (PSS) and then epitaxially growing a semiconductor layer on the concave-convex patterns.
However, such concave-convex patterns may cause crystal defects in the epitaxial semiconductor layer. Thus, a method capable of improving light extraction efficiency while reducing such crystal detects caused by concave-convex patterns is required.